Created
July 6, 2019 06:04
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| monitor DiningPhilosophers | |
| { | |
| enum {THINKING, HUNGRY, EATING} state[5]; | |
| condition self[5]; | |
| void pickup(int i){ | |
| state[i] = HUNGRY; | |
| test(i); | |
| //假如沒辦法拿到筷子，進入condition variable self[i]的queue | |
| if(state[i] != EATING){ | |
| self[i].wait(); | |
| } | |
| } | |
| void putdown(int i){ | |
| state[i] = THINKING; | |
| //通知自己旁邊的哲學家，假如有人餓肚子(HUNGRY)的話，可以試著拿起筷子了。 | |
| test((i+4) % 5); | |
| test((i+1) % 5); | |
| } | |
| void test(int i){ | |
| //看自己的左邊與右邊的哲學家都沒在吃東西（沒拿起筷子），就可以開始吃了 | |
| if((state[(i+4) % 5] != EATING) && (state[i] == HUNGRY) && (state[(i+1) % 5] != EATING)){ | |
| state[i] = EATING; | |
| self[i].signal(); | |
| } | |
| } | |
| //對condition variable進行初始化 | |
| initialization_code(){ | |
| for(int i = 0; i < 5; i++){ | |
| state[i] = THINKING; | |
| } | |
| } | |
| } |
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